Apparatus for obtaining etchable deposits on printing cylinders



'-pwll 7, 1942. A.AA. EGLI ET AL 2,278,52

/YTFAHATUS FOR OBTAINING ETCHABLE DEPOSITS ON PRINTING CYLINDERS April 7, 1942. A. A. EGLI ET AL APPARATUS FOR OBTAINING TCHABLE DEPOSITS ON PRINTING CYLINDERS Filed Feb. 2"1,v 1938 2 sheets-sheet 2 /m/eho/"s: ARNOLD Auusr asu KARL BOKENKAMP by Halmuaiv Afro/wey.

Patented Apr. 7, 1942 APPARATUS vFOR. OBTAINING ETCHABLE DEPOSITS 0N PRINTING CYLDIDERS Arnold August Egli, Zurich, Bkenkamp, Hamburg, Germany, Langbein Pfanhauser Werke Switzerland, and Carl assignors to Aktiengesellschaft, Leipzig, Germany Application February 21, 193s, serial No. 191,760

' In Switzerland February 22, 1937 j 11 claims. It is known in galvanotechnics to use smooth lwork pieces in the coppering of cylinders or tubes, which prevent the formation of blisters on galvanic deposition and yield with certainty a substantially plane surface of deposited copper. Also a certain density and 'hardness of the by means not shown, and

deposited metal is obtained by the smooth work pieces. However a polishing action or the obtainment of a completely smooth homogeneous surface as is necessary e. g. for etchable'printing cylinders cannot be achieved. In order to make the copper surfaces of the cylinders etchable these must always be submitted to a special polishing process.

It has no w been found thatwith the help of smooth rollers, etchable galvanic copper deposits can be obtained if certain technical conditions which form the object of the invention are maintained.

According' to the invention an agate roller fed to and fro, rolls on the rotating cylinder in such a manner that its position and direction can adjust themselves freely and automatically. Hereby a free rolling, as frictionless as possible, is adorded and any slipping, drawing or pushing of the agate roller on the cylinder surface is avoided. Moreover, according to. the invention the roller is increasingly loaded during the electroplating. By this treatment a copper deposit is obtained which after removal of the cyl inder from the bath needs only rubbing dry with a rag or paper, to be immediately etchable. Any grinding or polishing is superfluous which is of special advantage in printing cylinders of which the surface layer serving foretching is only so strong that it suffices for the time being for one etching and after the finish or printing is removed as a copper skin or turned down. Further characteristios of the process and the ap paratus serving to carry it out are given by the vfollowing 'description of one example of carrying the invention into effect.

Figure i is a perpendicular section through a galvanic bath and shows an apparatus formed according to the invention in two positions.

. Figure 2 is a plan view ofFigure v1 in which the weight carrying arm isbroken away.

Figure 3 shows'.a..smoothing roller with its holder in .elevationv Figure 4 is aside view, an

Figure 5 -a front view of Figure 3. In the trough I are arranged the anode holders 2 with the anodes 3 while the cylinder to be coppered 4, dips partly into the bath as cathode and is rotated -in the direction of the arrow 1). The screw shaft 5 is regulably driven turns alternately to the right and left. correspondingly the slide 6 carried by the shaft 5 is slowly moved to and fro with the nuts l.

The speed of rotation of the cylinder 4 and the displacement of the slide on the spindle 5 are preferably so correlated that with one-revolution of the cylinderthe sideways displacement of the smoothing roller will amount to about a third of the width of the path of contact of the roller with the cylinder, so that in traveling a helical path over the surface of the cylinder the edges of the path of contact will overlap.

(Fig.

On the arm 8 of the slide 6 a double bearing 9 of the arm 8 is a bolt II to take up the pierced In the double bearing 9 is al weight plates I2. rotatable spindle I3 which is displaceable in the axial direction and may be held by the collars I4 in order to be able continuously to adjust the smoothing roller.i6 to be vertically above the cylinder 4. So that the axis of the spindle I3 serving for adjustment may form a tangent as far as possible to the smoothing roller I6 4the bearing fork I5 is correspondingly bent. Thereby a tilting movement produced by the feeding forward of the spindle is avoided.

The displacement of the slide 6 causes the roller I6 to roll in a screw-line on the cylinder. If the axis of the roller were to be, as in the known processes, parallel to the axis of the cylinder, it would have an angle to its lineV of mor tion and the roller could not roll without slipping. By the movability in all directions of the roller provided according ,to the invention this adjusts itself however automatically in the very direction of its rolling, and also even for. the change of direction at the two ends of the cylindex', and also for cylinders of different diameter. Larger cylinders produce merely for the same displacement of the slide 6 a smaller angle of inclination than small cylinders. In order that the roller I6 may also accurately adjustitself automatically at the cylinder ends the shaft I3 is capable of rocking about the bolt lI0 of the double bearing 9. Moreover the roller IB must be capable of automatic adjustment on the cylinder so that especia-ily on reversal, slipping is avoided.

By these two possibil ties of adjustment a rolling free from slip is afforded.- Hindrances to free rotation which otherwise produce a vibration of the roller and al hammeredeiect on the copper can no longer occur. By a tube `I1 and hind the roller I8 which flows from the roller -on to the cylinder. The occurrence of a dry space behind the roller, which would favor oxidation and stripe formation, is thus avoided.

The diameter of the roller decreases from that of the cylindrical middle part about 3 cm.. wide, towards both side faces in a curve, as is obvious from Figures 3 to 5. The stationary stones I9 which act on both ends of the cylinder, serve to prevent blister formation at the edges of the cylinder and to smooth these edges.

The process is according to the invention, by the use of the apparatus shown as example,car ried out as follows:

At the beginning of the galvanic copper deposition on the cylinder, the agate roller is allowed to roll without additional pressure on the cylinder surface. After about one third of the time necessary to form an etchable layer has passed the roller is loaded by adding weights of about 10 kg. About half an hour before the ending of the coppering the current density is reduced by half. After the conclusion of the coppering the current is wholly switched off, but the cylinder submitted to a further treatment with the Thereupon, before'the cylinder is removed from the bath, the current is switched on for a short time in the reversed direction in order that to the axis of and above said base so as to roll uniformly over the deposit on said base, means attaching said roller to said slide so as to be freely bodily shiftable with respect to said slide during reciprocation thereof about an axis perpendicular to the common tangential plane of the base and roller and spaced from the point of tangency, whereby said roller can freely Aroll over said base in reversed helical paths without sliding as the result of the rotation of said base and the reciprocation of said slide.

2.l An electroplating apparatus including a rotating cylindrical base, a roller having a cylindrical central portion terminating in curved end portions of gradually decreasing diameter journalled for free rotation about an axis parallel to considerably higher loaded roller (20-30 kg.)..

or approximately parallel to the axis of rotation of said base,y means to reciprocate said roller to and fro endwise of its axis of rotation above said 1^ base, means permitting movement of said roller away from the axis of said base asthe base diameter changes and a pivoted connection between said last-mentioned means and said roller wherein the pivot has an axis substantially perpendicular to the common tangential plane of the roller and base and spaced from the point of tangency permitting free shifting of the roller axis upon rotation of said base and reciprocation of said roller so that the roller will automatically roll over the base in helical paths without sliding.

3. An electroplating apparatus including a roa sponge I8 bath liquid is supplied directly be-v drical' base so as to roll over the deposit as it is plated thereon, a slide, means to reciprocate said slide endwise of said base, and mechanism connecting said roller to said slide, said mechanism including a first pivoted connection having its axis substantially perpendicular to the common tangential plane of the base and roller and substantially spaced from the point of tangency, and a second pivoted connection having its axis lying substantially parallel to said common tangential plane, substantially'intersecting the axis of said first pivoted connection, and substantially lperpendicular to the axis of said roller.

4. An apparatus as claimed in claim 3 in which said roller comprises a cylindrical central portion terminating in end portions of smaller diameter curving slightly inwardly Ifrom said central portion towards theends of the roller.

5. An apparatus for producing etchable deposits upon a rotating cylindrical base, comprising an idle roller journalled above said base for rotation about an axis substantially parallel to the axis of the base so as to roll over and exert pressure on the deposit as it is plated thereon, said roller having a cylindrical center portion and gradually tapered ends, means to permit variation of the pressure exerted by said roller, and mechanism movable parallel to the length of the cylinder to pull said roller freely over said base on helical paths without relative sliding of the roller with respect to the base, including a pivotal mounting for said roller rotatable about an axis substantially perpendicular to the common tangential plane of the roller and cylinder and spaced from the point of tangency.

6. An apparatus for producing etchable deposits upon a rotating cylindrical base, comprising means to smooth the end edges of the deposit upon said base, an idle roller journalled above said base for rotation about an axis substantially parallel to that of the base so as to roll over `said base and exert pressure on the deposit between said edges as it is plated thereon and mechanism to move said roller freely over said base in helical paths from end to end without relative sliding of the roller with respect to the base, including means permitting pivotal movement of the roller about an axis substantially perpendicular to the common tangential plane of the roller and base and spaced from the point of tangency.

7. An apparatus for electroplating deposits upon a cylindrical base rotating about a horizontal axis, comprising a slide and mechanism to reciprocate said slide to and fro in a direction parallel to the axis of said base, an idle roller journalled on an axis substantially parallel to the axis of the base for rolling on said cylindrical. base, and means plvotally attaching said roller to said slide so as to swing freely about an axis substantially perpendicular to the common tangential plane of. the roller and cylindrical base and substantially spaced from the point of tangency, whereby said roller will track upon said base without sliding.

8. An apparatus for electroplating deposits upon a base having a continuous surface rotating about a horizontal axis. comprising a slide and means to reciprocate said slide to and fro along tating cylindrical base, an idle roller journalled 4 above .said cylindrical base for rotation about an axis substantially parallel to that of the cylina line parallel to the surface of the base, an idle roller journalled on an axis substantially parallel to the axis of the base, for rolling on said surface, kmeans p ermjtting movement of said roller away from theaxis of the cylinder, and lmeans pivotally attaching said roller to said slide so as to swing freely about an axis substantially perpendicular to the common tangential plane of the roller and surface and spaced from the point of tangency, whereby said roller will track upon said surface without sliding.

9. An apparatus for electroplating deposits upon a base having a continuous surface rotating about a horizontal axis, comprising a slide and means to reciprocate said slide to and fro along a line parallel to the surface of said base; a substan# tially horizontally journalled idle roller riding on said surface; a connection pivotally attaching said rollergto` said slide so as to swing freely about an axis substantially spaced from the point of tangency and substantially perpendicular to the common tangential plane of the roller and surface; said connection including means permitting said roller to pivot aboutlanlaxis lying substantially in said tangential plane and perpendicular to the roller axis.

10.- An apparatus for producing etchable deposits upon a rotating cylindricalbase, comprisng al roller J'ournalled above said base for free rotation about an axis substantially parallel to the axis of said base so as to roll over and exert pressure on the deposit as it is plated thereon, mechanism movable parallel to the length of the base, and means connecting said mechanism and roller to pull said roller freely over the base on helical paths without relative sliding of the roller with respect to the base, including a connection pivotable about an axis substantially perpendicular to the common tangential plane of the roller and base and spaced from the point of tangency.

11. An apparatus as claimed in claim 9 in which said roller comprises a cylindrical central portion terminating in end portions of smaller diameter curving slightly inwardly from said central portion towards the ends of the roller1 Y ARNOLD AUGUST EGLI. CARL BImNKAMP. 

